GB2128709A

GB2128709A - Drainage pipes

Info

Publication number: GB2128709A
Application number: GB8229630A
Authority: GB
Inventors: C J Cawte
Original assignee: Individual
Current assignee: Individual
Priority date: 1982-10-16
Filing date: 1982-10-16
Publication date: 1984-05-02

Abstract

Land drainage pipes which can be transported as substantially flat plastic strip ready for forming into a cylindrical pipe together with a method and apparatus therefor are described. The plastic strip eg PVC or polyolefine may be transversely corrugated and the longitudinal edges thereof are suitably adapted for joining, e.g. by means of a cooperating "snap" fastener, welding, glueing or bolting. The apparatus includes a suitably profiled shaping means (8) for rolling the sides of the plastic strip together for joining, and where an uncorrugated strip is used the apparatus may include downstream corrugating and perforating means (11, 12). <IMAGE>

Description

SPECIFICATION Drainage pipes The present invention relates to drainage pipes and in particular land drainage pipes which can be transported as a substantially flat strip ready for forming into a cylindrical pipe.

Traditionally, land drainage pipes have consisted of rigid, relatively short (e.g. 30 cms long), cylindrical, porous clay pipes which are laid end to end to form a continuous pipe.

More recently, relatively long lengths of drainage pipe (up to 10 metres long) made from plastics materials, such as polyvinylchloride or a polyefin have been used. In these pipes water enters via a plurality of perforations located in the wall thereof.

In both cases, as can be readily appreciated,the transport of such pipes, particularly by vehicle, entails transporting articles with a high volume to weight ration, especially in the case of pipes made from plastics materials. Notsurprisingly therefore, transporting such pipes has frequently been found to be commensurately uneconomic and in the case of plastic pipes has often had the effect of significantly increasing the overall cost of laying a drainage system.

In an attempt to improvethevolumeto weight ration of drainage pipes made from plastics materials, for transport purposes, it has been proposed to transversely corrugate the wall of the pipe, i.e. the corrugations running around the circumference ofthe pipe at right angles to the longitudinal axis thereof, so that the pipe can be coiled up, either as a flat coil or as a longitudinal coil. This solution has had some success, (e.g. 6 cm outside diameter pipes have been coiled in lengths of up to 100 metres), butthere still remains a "long felt want" to improve the volume to weight ratio still further and thereby minimise the cost of transporting what is effectively, a great deal of "empty space".

Increasing the flexibility of the pipe by corrugating also improves the ease with which the pipe may subsequently be laid bytrenchless laying, i.e. into a "closed" trench.

The present invention seeks to meet such "long felt want" by providing a plastics pipe priortoits cylindrical forming, which thereby possesses a significantly reduced volumeto weight ratio.

The present invention also seeks to provide a plastics pipe which meets the British Standards Institution specification for "Plastics pipes for use as light duty sub-soil drains" (BS4962: 1982).

Accordingly, the present invention provides a sub stantially flat flexible plastics material strip the longitudinal edges of which are suitably adapted so that they may be joined together to form a cylindrical pipe.

The present invention also provides a method for forming a cylindrical pipe from a substantially flat flexible plastics material strip in which the longitudinal edges of the strip are rolled inwards and suitably joined together.

The present invention further provides apparatus for forming a cylindrical pipe from a substantially flat flexible plastics material strip comprising shaping means suitably profiled to bring the longitudinal edges of the strip togetherforjoining and means for withdrawingthestripfrom shaping means.

Preferably, the material strip comprises a plastics material such as unplasticised polyvinylchloride, or polyethylene or polypropylene.

Advantageously, the wall of the pipe is transversersely corrugated in order to improve its flexibility for ease of laying. Thus, a pipe may be formed from a pre-corrugated plastics strip which is preferred, or, alternatively the pipe may be corrugated immediately afterforming, by passing through a hot corrugating clamping press. In either case the drainage perforations are desirably made in the wall of the pipe after corrugating, e.g. by punching, and are located in the "troughs" of the corrugationsforefficient hydraulic performance.

Fora precorrugated strip, a marginal portion extending along each ofthe longitudinal edges is advantageously left uncorrugated and flatto facilitate joining as described below.

A plastics "pipe" according to the present invention would therefore be transported as a substantially flat strip which could readily be coiled or stacked as pre-cut lengths to give a very low volume to weight ratio, thereby dramatically improving the cost of transporting such "pipes". For a 6 cm outside diameter pipe, the present invention represents at least a 300% saving in terms ofthevolumeto weight ratio, which increases to at least a 700% saving for a 16 cm outside diameter pipe.

If strip is pre-corrugatedthen improved stability of load may be obtained by virtue of the cooperation of corrugations on adjacent portions of strip.

As will be appreciated, the flat plastics strip is substantially equivalent to an existing cylindrical pipe which had been longitudinally slit and laid flat.

Advantageou Isy, the join i ng together of the longitudinal edges of the strip is carried out atthe point of laying the pipe, preferably by a suitable attachment to the pipe laying machine. The longitudinal edges of the strip may be suitably adapted for joining by the provision of a cooperating "snap" ball and socket or hook fastening, which may extend continuously along the length of the edges ofthe strip. Alternatively, the edges may be welded (e.g. by heating or solvent welding), glued or riveted, with orwithoutthe use of an overloading longitudinal strip.

In the practice of the present invention, a mechanical "snap" fastener arrangement is preferred.

By way of further exemplary illustration of the present invention, reference is made to the accompanying drawings, in which Figure 1 is a diagrammatic perspective view of a coiled, transversely corrugated length of pve "pipe" intheform of strip, and Figure 2 is a diagrammatic part perspective view of a suitable edge joining apparatus comprising a "converging" diethrough which the strip is drawn, and optionally, wall corrugating and perforation punching devices.

As can readily be seen, the transport of a "pipe" strip 1 as shown in Figure 1 will result in a very low volume to weight ratio with a commensurate saving in transport costs. The strip may be coiled or stacked in pre-cut lengths. If transversely corrugated 1 ate stability of the coiled strip or stack of pre-cut lengths will be improved by the partial meshing together of adjacent corrugations.

Drainage perforations 2 made by "punching out" are located at regular intervals in the troughs of the corrugations along the length of the strip, for example, in a typical 6 cm outside diameter pipe, three perforations 3 mm x 1 mm in size may be symmetrically arranged along the strip in adjacent corrugation troughs at approximately 1 cm. intervals.

The uncorrugated, flat marginal edges4, 5 orthe strip possess respectively male and female members 6 7 to provide a friction "snap" fastener when the edges are brought together as shown in Figure 2.

The bringing together and fastening of the male and female members 6 7 may be conveniently achieved by a suitably profiled, heated and lubricated die 8 (alternatively, shaping rollers can be employed) which causes the corrugated strip to soften and the side portionsthereofto be rolled orcurled inwards and joined to form a continuous cylindrical pipe 9, as the strip is slowly drawn through the die by fluted rollers 10.

When the wall ofthepipeisto be corrugated following pipe forming, this may be readily achieved byasuitablecorrugated hot clamping press 11, located downstream of the die and preferably immediately thereafter. The press may simply comprise two cooperating sections movable in the direction of the pipe which are heated to an appropriate temperature and broughttogetherto corrugate successive portions oftheformed plastic pipe. Drainage perforations are then "punched out" in successive corrugation troughs by conventional means 12 downstream oftheclamping press.

Claims

1. A substantially flat flexible plastics material strip the longitudinal edges of which are suitably adapted so that they may bejoined together to form a clyindrical pipe.

2. A plastics material strip according to Claim 1 comprising unplasticised polyvinylchloride.

3. A plastics material strip according to Claim 1 comprising a polyolefin.

4. Astrip according to anyone of Claims 1 to 3 which is transversely corrugated.

5. A strip according to Claim 4 in which a marginal uncorrugated portion extends along each ofthe longitudinal edges of the strip.

6. Astrip according to Claim 4 or Claim Sin which drainage perforations are located in the troughs ofthe corrugations.

7. A strip according to any one of the preceding claims in which the longitudinal edges are adapted to be joined by means of a cooperating "snap" fastener.

8. A strip according to any one of Claims 1 to 6 in which the longitudinal edges are adapted to be joined by welding, glueing or riveting.

9. Amethodforforming acylindrical pipefroma substantiallyflatflexible plastics material strip in which the longitudinal edges of the strip are rolled inwards and suitably joined together.

10. A method according to Claim 9 in which the strip comprises u nplasticised polyvinylchloride.

11. A method according to Cliam 9 in which the strip comprises a polyolefin.

12. A method according to any one of Claims 9 to 11 in which the strip is transversely corrugated.

13. A method according to Claim 12 in which a marginal uncorrugated portion extends along each of the longitudinal edges of strip.

14. A method according to Claim 12 or Claim 13 in which drainage perforations are located in the troughs ofthe corrugations.

15. A method according to any one of Claims 9 to 14 in which the longitudinal edges are joined by means of a cooperating "snap" fastener.

16. A method according to any one of Claims 9 to 14 in which the longitudinal edges are joined by welding, glueing or riveting.

17. A method according to Claim 9 in which the wall ofthe pipe is corrugated and perforations made following pipe forming.

18. Apparatusforforming a cylindrical pipe from a substantiallyflatflexible plastics material strip cm prising shaping means suitably profiled to bring the longitudinal edges of the strip togetherforjoining and meansforwithdrawingthestripfrom shaping means.

19. Apparatus according to Claim 18 in which a corrugated clamping press is located downstream of the shaping means.

20. Apparatus according to Claim 19 in which perforating means are located downstream of the clamping means.

21. A substantially flat flexible plastics material strip substantially as hereinbefore described with reference to Fig. 1 ofthedrawings.

22. Amethodforforming a cylindrical pipe from a substantially flat flexible plastics material strip substantially as hereinbefore described with reference to Fig. 2 ofthe drawings.

23. Apparatus forforming a cylindrical pipe from a substantially flat flexible plastics material strip substantially as hereinbefore described with reference to Fig. 2 of the drawings.